The present invention relates to a machine and a method for the treatment of liquid and semi-liquid food mixtures.
The present invention relates in particular, although without limiting the scope of the inventive concept, to machines for producing and treating crushed-ice drinks, sorbets, ice creams, soft ice creams, cream, yoghurt and the like and to pasteurizing machines and to machines for cooking, processing and preserving mixtures, creams, sauces, soups and mixtures in general and the like.
Machines of the type described above comprise a container or tank for the food product or mixture to be treated, more commonly known as a whipping and freezing/heating unit, means for heating and/or cooling it, and if necessary means for dispensing it, for example consisting of nozzles or taps designed to allow the end product (whipped cream, ice cream, crushed-ice drink, etc.) to be drawn out.
A feed circuit conveys the basic products of which the mixture consists, comprising for example liquid cream, mixtures of products for ice cream, syrups and the like, into the product treatment and processing tank.
To homogeneously mix together the basic products introduced into the whipping and freezing/heating unit, and to render even, during the heating or the cooling, the temperature of the entire mass of product being processed, there are also rotary mixing blades inside the whipping and freezing/heating unit.
A first motor, usually electric, controls the rotation of the mixing blades and a second motor, also preferably electric, drives a compressor which is part of the heating and/or cooling means.
The basic products usually have different temperatures and consistencies: during their processing, the temperature of the container and the continuous mixing action cause a change in the physical state, and therefore the consistency of the product, which gradually becomes more homogeneous, softer and denser.
During product processing, the temperature of the tank or whipping and freezing/heating unit must vary, increasing, for the preparation of creams, or reducing, for the preparation of ice creams. In both cases the motor which drives the compressor must vary its speed of rotation to regulate the compressor displaced volume and therefore the system refrigerating capacity. The mixing speed must also be regulated in time depending on the temperature reached by the entire mixture and the consistency of the food product. For some preparations, an inadequate mixing speed may irreversibly compromise the success of the end product. The temperature reached by the mixture in a predetermined time interval and the level of softness also depend on the quantity of mixture treated.
Conventional machines are sized to operate in optimum conditions only at a predetermined load of product to be treated. In other words, such machines operate in optimum temperature, mixing speed and energy consumption conditions only with a predetermined quantity of product, usually close to the tank maximum load.
Therefore, to avoid wasting energy, the machines must always operate in optimum conditions, that is to say, they must operate by treating a quantity of product close to the maximum value for which they were sized.
Disadvantageously, sometimes that may involve wasting basic products.